U.S. patent number 8,033,332 [Application Number 12/624,195] was granted by the patent office on 2011-10-11 for apparatus and method for perforating and fracturing a subterranean formation.
This patent grant is currently assigned to Owen Oil Tools, LP. Invention is credited to Joseph Haney, Dan W. Pratt.
United States Patent |
8,033,332 |
Haney , et al. |
October 11, 2011 |
Apparatus and method for perforating and fracturing a subterranean
formation
Abstract
A device for perforating and fracturing a formation in a single
trip includes shaped charges and a volume of a gas generator. When
activated by detonation of the shaped charges, the gas generator
forms a high-pressure gas, which includes steam, that expands to
stress and fracture the formation. Suitable gas generating
materials include hydrates and hydroxides. Other materials that can
be employed with the gas generator include oxidizers and material
such as metals that increase the available heat for the activation
of the gas generator.
Inventors: |
Haney; Joseph (Bayview, ID),
Pratt; Dan W. (Benbrook, TX) |
Assignee: |
Owen Oil Tools, LP (Houston,
TX)
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Family
ID: |
37947094 |
Appl.
No.: |
12/624,195 |
Filed: |
November 23, 2009 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100065274 A1 |
Mar 18, 2010 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11252958 |
Oct 18, 2005 |
7621332 |
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Current U.S.
Class: |
166/298;
166/308.1 |
Current CPC
Class: |
E21B
43/117 (20130101); E21B 43/26 (20130101) |
Current International
Class: |
E21B
43/117 (20060101); E21B 43/263 (20060101) |
Field of
Search: |
;166/298,308.1,308.2,308.3,297 ;102/313,314,318,320,321,322
;89/1.15,1.151 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Thompson; Kenneth L
Attorney, Agent or Firm: Mossman, Kumar & Tyler, PC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of and claims priority to U.S.
patent application Ser. No. 11/252,958 filed Oct. 18, 2005.
Claims
What is claimed is:
1. A method for perforating and fracturing a formation, comprising:
positioning a gas generator internal to a charge tube and external
to a plurality of shaped charges affixed to the charge tube;
initiating a detonation of the plurality of shaped charges;
creating a plurality of perforating jets for penetrating the
formation to form perforations in the formation; releasing thermal
energy by the detonation of the plurality of shaped charges;
creating a high-pressure gas by using carbon, the thermal energy
released by the detonation of the plurality of shaped charges, and
the gas generator; and stressing the perforations using the
high-pressure gas.
2. The method according to claim 1, further comprising: increasing
an available heat by using aluminum.
3. The method according to claim 1, further comprising releasing
oxygen to create the high-pressure gas using an oxidizer.
4. The method according to claim 3, further comprising combining
the oxygen with a metal fuel.
5. A method for perforating and fracturing a formation, comprising:
releasing thermal energy by detonating a plurality of shaped
charges in a wellbore to form perforations in the formation;
creating a high-pressure gas by using carbon, the thermal energy
released by the detonation of the plurality of shaped charges, and
a gas generator; releasing oxygen to create the high-pressure gas
using an oxidizer; combining the oxygen with a metal fuel; and
stressing the perforations using the high-pressure gas.
6. The method according to claim 5, further comprising: increasing
an available heat by using aluminum.
7. The method according to claim 5, further comprising: positioning
the gas generator internal to a charge tube and external to the
plurality of shaped charges affixed to the charge tube.
8. A method for perforating and fracturing a formation, comprising:
forming perforations in the formation using a plurality of
perforating jets; creating a high-pressure gas by using carbon, a
thermal energy released during the formation of the plurality of
perforating jets, and a gas generator; releasing oxygen to create
the high-pressure gas using an oxidizer; combining the oxygen with
a metal fuel; and stressing the perforations using the
high-pressure gas.
9. The method according to claim 8, further comprising: increasing
an available heat by using aluminum.
10. The method according to claim 8, further comprising:
positioning the gas generator internal to a charge tube and
external to a plurality of shaped charges affixed to the charge
tube.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for
perforating well casing and/or a subterranean formation. More
particularly, the present invention relates to an apparatus and
process wherein a propellant is conveyed into a well within a
shaped charge.
2. Description of the Related Art
Hydrocarbon producing wells typically include a casing string
positioned within a well bore that intersects a subterranean oil or
gas deposit. The casing string increases the integrity of the well
bore and provides a path for producing fluids to the surface.
Conventionally, the casing is cemented to the well bore face and
subsequently perforated by detonating shaped explosive charges.
These perforations extend through the casing and cement a short
distance into the formation. In certain instances, it is desirable
to conduct such perforating operations with the pressure in the
well being overbalanced with respect to the formation pressure.
Under certain overbalanced conditions, the well pressure exceeds
the pressure at which the formation will fracture, and therefore,
hydraulic fracturing occurs in the vicinity of the perforations. As
an example, the perforations may penetrate several inches into the
formation, and the fracture network may extend several feet into
the formation. Thus, an enlarged conduit can be created for fluid
flow between the formation and the well, and well productivity may
be significantly increased by deliberately inducing fractures at
the perforations.
Techniques for perforating and fracturing a formation surrounding a
borehole are known in the art. The common technique of
hydraulically pressurizing the borehole to expand or propagate the
fractures initiated by the projectile can be expensive due to the
preparation required for pressurizing a portion of a borehole.
Typically, pressure around a production zone in the borehole is
increased by pumping fluids into that portion of the well to obtain
the high pressures necessary to expand the fracture in the
production zones. This operation is generally time intensive and
costly making these techniques unattractive for either multiple
zone wells or wells with a low rate of production.
Gas generating propellants have been used in place of hydraulic
fracturing techniques to create and propagate fractures in a
subterranean formation. In one conventional arrangement, a
perforating gun having shaped charges is fitted with a propellant
charge and conveyed into the well. This propellant charge may be
formed as a sleeve that surrounds a charge tube in which the shaped
charges are secured. As is known, flammable or combustible material
such as propellants require careful handling during all aspects of
manufacture, transportation and deployment. Thus, protective
measures are taken throughout all these phases to prevent
unintended detonation of the propellant.
Thus, it is one object of this invention to provide methods and
systems for safely and efficiently fracturing a well, particularly
in connection with a perforation activity. Still other objects will
become apparent below.
SUMMARY OF THE INVENTION
The present invention provides devices and methods for safely and
efficiently fracturing a formation. In one aspect, these devices
and methods are adapted to perforate and fracture the formation in
a single trip. An exemplary device for perforating and fracturing a
subterranean formation includes shaped charges and a volume of a
gas generator (or gas generating material). When activated, the gas
generator forms a high-pressure gas that includes steam. The
high-pressure gas expands to stress and fracture the formation. The
gas generator is activated by a downhole energy source. Suitable
gas generating materials include hydrates and hydroxides. Theses
classes of material can be activated using thermal energy released
by detonation of shaped charges. Other materials that can be
employed with the gas generator include oxidizers and material such
as metals that increase the available heat for the activation of
the gas generator.
In embodiments where the gas generator is used in connection with a
perforating gun, one or more parts of the gun can be formed from
the gas generator. For example, one or more casings for the shaped
charges can be formed from the gas generator. In situations where
fracturing is not done in connection with another activity such as
perforating, an exemplary device having a volume of a gas generator
can be conveyed down using a suitable conveyance device.
The above-recited examples of features of the invention have been
summarized rather broadly in order that the detailed description
thereof that follows may be better understood, and in order that
the contributions to the art may be appreciated. There are, of
course, additional features of the invention that will be described
hereinafter and which will form the subject of the claims appended
hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
For detailed understanding of the present invention, references
should be made to the following detailed description of the
preferred embodiment, taken in conjunction with the accompanying
drawings, in which like elements have been given like numerals and
wherein:
FIG. 1 is a schematic sectional view of one embodiment of an
apparatus of the present invention as positioned within a well
penetrating a subterranean formation;
FIG. 2 is a schematic sectional view of a portion of the FIG. 1
embodiment; and
FIG. 3 is a flowchart illustrating embodiments of methods for
perforating and fracturing a formation according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
As will become apparent below, the present invention provides a
safe and efficient device for fracturing a subterranean formation.
In aspects, the present invention uses a gas generating material
that, when activated, produces a high-pressure gas having a steam
component. The steam can be a fraction or substantially all of the
high-pressure gas generated. Merely for convenience, suitable
materials that decompose to release water will be referred to as
steam-producing materials. Exemplary materials include hydrates and
hydroxides. Hydrates are compounds formed by the union of water
molecules with some a primary material. Common hydrates include
gypsum (calcium sulfate dihydrate), barium chloride dihydrate,
lithium percholorate trihydrate and magnesium carbonate
pentahydrate. Hydroxides are compounds that contain one or more
hydroxyl groups. Common hydroxides include magnesium hydroxide. As
should be appreciated, such materials can be manufactured,
transported and deployed without the safeguards typically used when
handling combustible materials such as propellants. Embodiments
utilizing steam-producing material for fracturing are discussed in
greater below.
Referring initially to FIG. 1, there is shown a perforating gun 10
disposed in a wellbore 12. Shaped charges 14 are inserted into and
secured within a charge holder tube 16. A detonator or primer cord
18 is operatively coupled in a known manner to the shaped charges
14. The charge holder tube 16 with the attached shaped charges 14
are inserted into a carrier housing tube 20. Any suitable
detonating system may be used in conjunction with the perforating
gun 10 as will be evident to a skilled artisan. The perforating gun
10 is conveyed into the wellbore 12 with a conveyance device that
is suspended from a rig or other platform (not shown) at the
surface. Suitable conveyance devices for conveying the perforating
gun 10 downhole include coiled tubing, drill pipe, a wireline,
slick line, or other suitable work string may be used to position
and support one or more guns 10 within the well bore 12. In some
embodiments, the conveyance device can be a self-propelled tractor
or like device that move along the wellbore. In some embodiments, a
train of guns may be employed, an exemplary adjacent gun being
shown in phantom lines and labeled with 10'.
In one embodiment, the perforating gun 10 is configured to
perforate and fracture a formation in a single trip, the
perforations being enumerated with P and the fracturing action
being enumerated with F. As will be described more fully below, the
material for producing a high-pressure gas for fracturing the
formation 13 is carried in a suitable location along the gun
10.
Referring now to FIG. 2, there is illustratively shown a section of
the perforating gun 10. In FIG. 2, there is sectionally shown the
shaped charge 14, the charge tube 16, and the carrier tube 20. In
one arrangement, a volume of steam-producing material, shown with
dashed lines and labeled 30, can be positioned external to the
carrier tube 20. For example, the external volume of
steam-producing material 30 can be formed as a sleeve or strip
fixed onto the carrier tube 20. In another arrangement, a volume of
steam-producing material, shown with dashed lines and labeled 32,
can be positioned internally within the carrier tube 20 and
external to the charge tube 16. In another arrangement, a volume of
steam-producing material, shown with dashed lines and labeled 34,
can be positioned internal to the charge tube 16. Additionally, a
volume of steam-producing material can be positioned adjacent to
the shaped charges 16 such as in an adjoining sub (not shown).
In still other embodiments, one or more elements making up the
perforating gun 10 can be formed from the steam-producing material.
For example, a casing 36 of the shaped charge 16 can be formed
partially or wholly from a steam-producing material. In another
arrangement, a volume of steam-producing material 38 can be
positioned inside the casing 38. In still other arrangements, the
carrier tube 20, charge tube 16 or other component of the
perforating gun 10 can be formed at least partially of a
steam-producing material.
Referring now to FIG. 3, there is shown illustrative methodologies
for utilizing steam-producing material to fracture a formation. In
connection with a perforating gun as shown in FIG. 1, a method for
fracturing a formation with steam-producing material can be
initiated by detonation of one or more perforating charges at step
110. In a conventional manner, the detonation creates a perforating
jet at step 110 that penetrates the formation at step 120 and forms
a perforation in the formation at step 130. In one arrangement, the
detonation step 100 releases thermal energy at step 140 that
activates the steam-producing material at step 150. By activate, it
is meant that the steam-producing material undergoes a change in
material state or composition. The activated steam-producing
material creates a high-pressure gas that has a steam component at
step 160. For example, upon application of thermal energy, a
hydrate decomposes and releases water that nearly instantly is
converted to steam. At step 170, the expansion of the high-pressure
gas stresses the wellbore and in particular the perforations made
at step 130. At step 180, the formation and in particular the
perforations fracture.
In one variant, the detonation step 100 can generate a gas or other
material at step 190 that activates the steam-producing material at
step 150. For example, the gas or other material can chemically
interact with the steam-production material. Such an interaction
(i.e., chemical activation) can be used in combination with or in
lieu of thermal activation. Other activation methods, which may or
may not use detonation of a shaped charge, include pressure
activation and electrical activation. Advantageously, a gas
generated at step 190 can be used to supplement the high-pressure
gas formed at step 160 to stress the formation at step 170.
It should be appreciated that while the FIG. 3 methodologies are
particularly suited for perforating and fracturing a formation in a
single trip, embodiments of the present invention can fracture a
formation independent of a perforating gun or other wellbore
tool.
In certain applications, an oxidizer may be used in conjunction
with the gas generating material. Suitable oxidizers include
potassium sulfate and potassium benzoate. The oxygen released by
the oxidizers can combine with a metal fuel such as zinc and/or
with carbon or hydrogen (e.g., rubber). Also, materials such as
calcium sulfate hemihydrate can function as both a hydrate and a
high temperature oxidizer. Additionally, material can be used in
conjunction with the gas generating material to increase the
available heat of reaction. Suitable material includes a metal such
as finely divided aluminum.
The foregoing description is directed to particular embodiments of
the present invention for the purpose of illustration and
explanation. It will be apparent, however, to one skilled in the
art that many modifications and changes to the embodiment set forth
above are possible without departing from the scope of the
invention. Thus, it is intended that the following claims be
interpreted to embrace all such modifications and changes.
* * * * *